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| // 抽象产品 - 日志记录器接口
interface Logger {
void log(String level, String message);
void info(String message);
void error(String message);
void debug(String message);
}
// 具体产品 - 文件日志记录器
class FileLogger implements Logger {
private String filename;
public FileLogger(String filename) {
this.filename = filename;
}
@Override
public void log(String level, String message) {
String logEntry = String.format("[%s] %s: %s",
new Date().toString(), level, message);
System.out.println("写入文件 " + filename + ": " + logEntry);
}
@Override
public void info(String message) { log("INFO", message); }
@Override
public void error(String message) { log("ERROR", message); }
@Override
public void debug(String message) { log("DEBUG", message); }
}
// 具体产品 - 控制台日志记录器
class ConsoleLogger implements Logger {
private String prefix;
public ConsoleLogger(String prefix) {
this.prefix = prefix;
}
@Override
public void log(String level, String message) {
System.out.println(String.format("[%s][%s] %s: %s",
prefix, new Date().toString(), level, message));
}
@Override
public void info(String message) { log("INFO", message); }
@Override
public void error(String message) { log("ERROR", message); }
@Override
public void debug(String message) { log("DEBUG", message); }
}
// 具体产品 - 数据库日志记录器
class DatabaseLogger implements Logger {
private String tableName;
public DatabaseLogger(String tableName) {
this.tableName = tableName;
}
@Override
public void log(String level, String message) {
String sql = String.format("INSERT INTO %s (level, message, timestamp) VALUES ('%s', '%s', '%s')",
tableName, level, message, new Date().toString());
System.out.println("数据库记录日志：" + sql);
}
@Override
public void info(String message) { log("INFO", message); }
@Override
public void error(String message) { log("ERROR", message); }
@Override
public void debug(String message) { log("DEBUG", message); }
}
// 抽象工厂 - 日志工厂
abstract class LoggerFactory {
public abstract Logger createLogger();
// 便捷的静态工厂方法
public static LoggerFactory getFactory(String type, String config) {
switch (type.toLowerCase()) {
case "file":
return new FileLoggerFactory(config);
case "console":
return new ConsoleLoggerFactory(config);
case "database":
return new DatabaseLoggerFactory(config);
default:
throw new IllegalArgumentException("未知的日志类型: " + type);
}
}
}
// 具体工厂实现
class FileLoggerFactory extends LoggerFactory {
private String filename;
public FileLoggerFactory(String filename) {
this.filename = filename;
}
@Override
public Logger createLogger() {
return new FileLogger(filename);
}
}
class ConsoleLoggerFactory extends LoggerFactory {
private String prefix;
public ConsoleLoggerFactory(String prefix) {
this.prefix = prefix;
}
@Override
public Logger createLogger() {
return new ConsoleLogger(prefix);
}
}
class DatabaseLoggerFactory extends LoggerFactory {
private String tableName;
public DatabaseLoggerFactory(String tableName) {
this.tableName = tableName;
}
@Override
public Logger createLogger() {
return new DatabaseLogger(tableName);
}
}
// 应用程序示例
public class LoggerFactoryDemo {
public static void main(String[] args) {
// 根据配置创建不同类型的日志记录器
String logType = "file"; // 可以从配置文件读取
String logConfig = "application.log";
LoggerFactory factory = LoggerFactory.getFactory(logType, logConfig);
Logger logger = factory.createLogger();
logger.info("应用程序启动");
logger.debug("调试信息：初始化完成");
logger.error("发生错误：连接数据库失败");
// 切换到控制台日志
LoggerFactory consoleFactory = LoggerFactory.getFactory("console", "MyApp");
Logger consoleLogger = consoleFactory.createLogger();
consoleLogger.info("切换到控制台日志");
consoleLogger.debug("这是控制台调试信息");
// 使用数据库日志
LoggerFactory dbFactory = LoggerFactory.getFactory("database", "application_logs");
Logger dbLogger = dbFactory.createLogger();
dbLogger.info("数据库日志记录");
dbLogger.error("数据库错误日志");
}
}
|